<!DOCTYPE html>
<html>
<head>
<title>Table border collapse</title>
<style>
  table {
    border-collapse: collapse;
  }
  tr.odd {
    background-color: LightCyan;
  }
  tr.even {
    background-color: LightSkyBlue;
  }
  td {
    border: 5px solid DarkBlue;
  }
  caption {
    height: 10px
  }
</style>
</head>
<body>
  <table>
    <caption></caption>
    <tr class="odd">
      <td>Cell 1-1</td>
      <td>Cell 1-2</td>
    </tr>
    <tr class="even">
      <td>Cell 2-1</td>
      <td>Cell 2-2
        <table>
          <tr class="odd">
            <td>Cell 2-2/1-1</td>
            <td>Cell 2-2/1-2</td>
          </tr>
          <tr class="even">
            <td>Cell 2-2/2-1</td>
            <td>Cell 2-2/2-2</td>
          </tr>
        </table>
      </td>
    </tr>
  </table>
</body>
</html>